1-Acylthiosemicarbazides, 1,2,4-triazole-5(4H)-thiones, 1,3,4-thiadiazoles and hydrazones containing 5-methyl-2-benzoxazolinones: Synthesis, analgesic-anti-inflammatory and antimicrobial activities

Abstract Acetic acid hydrazide containing 5-methyl-2-benzoxazolinone ( 4 ) was synthesized by the condensation of 2-(5-methyl-2-benzoxazolinone-3-yl)acetate with hydrazine hydrate. Thiosemicarbazide derivatives ( 5a – 5d ) were afforded by the reaction of corresponding compound 4 with substituted isothiocyanates. The cyclization of compounds 5a – 5d in the presence of triethylamine resulted in the formation of compounds 6a – 6d containing 1,2,4-triazole ring. On the other hand, the treatment of compounds 5a – 5d with orthophosphoric acid caused the conversion of side chain of compounds 5a – 5d into 1,3,4-thiadiazole ring: thus, compounds 7a – 7c were obtained. The treatment of compound 4 with aromatic aldehydes resulted in the formation of arylidene hydrazides as cis – trans conformers ( 8a – 8e ). The structures of the compounds were elucidated by spectral and elemental analysis. While most compounds were exhibiting high activity in the analgesic-anti-inflammatory field, most of them were found to be inactive against bacteria and fungi.